SDN network system, controller, and controlling method

ABSTRACT

A software defined network (SDN) system, controller, and controlling method, where the SDN system includes at least one N th  level controller and at least two (N+1) th  level controllers belonging to the N th  level controller, where the (N+1) th  level controller is configured to receive a first message sent by a node belonging to the (N+1) th  level controller, and when the first message is a cross-domain message according to status information of each node that is managed by the (N+1) th  level controller, forward the first message to the N th  level controller to which the (N+1) th  level controller belongs, and the N th  level controller receives the first message, and perform decision processing according to status information of the (N+1) th  level controller that is managed by and belongs to the N th  level controller and status information of boundary nodes of the (N+1) th  level controller belonging to the N th  level controller.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Application No.PCT/CN2015/077397, filed on Apr. 24, 2015, which claims priority toChinese Patent Application No. 201410178870.8, filed on Apr. 29, 2014.The disclosures of the aforementioned applications are herebyincorporated by reference in their entireties.

TECHNICAL FIELD

The present disclosure relates to the field of communicationstechnologies, and in particular, to a software defined network (SDN)system, controller, and controlling method.

BACKGROUND

A SDN is a new network architecture in which control and management areseparated. In the SDN, a dedicated device deploys a high-level policy,and a network device forwards data under the guidance of the high-levelpolicy such that many complex functions carried by the network deviceare reduced, and flexibility and an entirety of a network can beimproved.

An OPENFLOW technology, as a southbound interface of an SDNarchitecture, is a key representative technology in the SDN field. In anOPENFLOW network, a topology and information of an entire network aremanaged using an OPENFLOW controller. In a large-scale data centerarchitecture or a cross-operator OPENFLOW network architecture, theOPENFLOW network is divided into different areas, and a controller isconfigured for each area. When receiving a data transmission request, acontroller calculates a network path according to networking informationstored in the controller, and sends a path out of a local domain to eachcorresponding controller. After receiving path information, thecorresponding controller directly sends the path information to aswitching node in a domain of the corresponding controller.

Each controller in the foregoing network architecture can acquire thenetworking information, and when a controller is attacked, thenetworking information is leaked.

SUMMARY

Embodiments of the present disclosure provide an SDN system, controller,and controlling method in order to resolve a problem in an existingnetwork architecture that each controller can acquire networkinginformation, and the networking information is leaked when a controlleris attacked.

According to a first aspect, an embodiment of the present disclosureprovides an SDN system, including at least one N^(th) level controllerand at least two (N+1)^(th) level controllers belonging to the N^(th)level controller, where N is an integer greater than or equal to 1,where the (N+1)^(th) level controller is configured to receive a firstmessage sent by a node belonging to the (N+1)^(th) level controller, andwhen the first message is a cross-domain message according to statusinformation of each node that is managed by the (N+1)^(th) levelcontroller and that belongs to the (N+1)^(th) level controller, forwardthe first message to the N^(th) level controller to which the (N+1)^(th)level controller belongs, and the N^(th) level controller is configuredto receive the first message forwarded by the (N+1)^(th) levelcontroller belonging to the N^(th) level controller, and performdecision processing according to status information of the (N+1)^(th)level controller that is managed by the N^(th) level controller and thatbelongs to the N^(th) level controller and status information ofboundary nodes of the (N+1)^(th) level controller belonging to theN^(th) level controller, where boundary nodes of each (N+1)^(th) levelcontroller include a node, which is connected to a node belonging toanother (N+1)^(th) level controller, of all nodes belonging to the(N+1)^(th) level controller, the first message includes an identifier ofthe node sending the first message, and the cross-domain messageincludes an identifier of the node belonging to the other (N+1)^(th)level controller.

In a first possible implementation manner of the first aspect, the(N+1)^(th) level controller is further configured to add an identifierof the (N+1)^(th) level controller to the first message, to obtain asecond message if the received first message includes an identifier ofanother (N+1)^(th) level controller. The (N+1)^(th) level controller isfurther configured to send the second message to the N^(th) levelcontroller to which the (N+1)^(th) level controller belongs, and theN^(th) level controller is further configured to receive a secondmessage sent by each (N+1)^(th) level controller belonging to the N^(th)level controller, and determine a backbone topology of the SDN systemaccording to the second message in order to determine a backbonetransmission path of data in the SDN system according to the backbonetopology.

With reference to the first possible implementation manner of the firstaspect, in a second possible implementation manner of the first aspect,the SDN system further includes at least one (N−1)^(th) levelcontroller, at least two N^(th) level controllers belonging to the(N−1)^(th) level controller, and at least four (N+1)^(th) levelcontrollers belonging to the at least two N^(th) level controllers,where N is an integer greater than 1, where the N^(th) level controlleris further configured to replace the identifier of the (N+1)^(th) levelcontroller in the second message with an identifier of the N^(th) levelcontroller, to obtain a third message if the second message includes anidentifier of an (N+1)^(th) level controller not belonging to the N^(th)level controller. The N^(th) level controller is further configured tosend the third message to the (N−1)^(th) level controller to which theN^(th) level controller belongs, and the (N−1)^(th) level controller isconfigured to receive the third message sent by the N^(th) levelcontroller belonging to the (N−1)^(th) level controller, and determinethe backbone topology of the SDN system according to the third messagein order to determine the backbone transmission path of the data in theSDN system according to the backbone topology of the SDN system.

With reference to the first or second possible implementation manner ofthe first aspect, in a third possible implementation manner of the firstaspect, the (N+1)^(th) level controller is further configured toseparately send a fourth message to the N^(th) level controller to whichthe (N+1)^(th) level controller belongs and a node belonging to the(N+1)^(th) level controller, where the fourth message includes anidentifier of the node to which the fourth message is sent and theidentifier of the (N+1)^(th) level controller. The N^(th) levelcontroller is further configured to receive the fourth message sent bythe (N+1)^(th) level controller belonging to the N^(th) levelcontroller, and the N^(th) level controller is further configured todetermine the backbone topology of the SDN system according to thesecond message and the fourth message that include an identifier of asame node in order to determine the backbone transmission path of thedata in the SDN system according to the backbone topology of the SDNsystem.

With reference to any one of the first aspect and the first to thirdimplementation manners of the first aspect, in a fourth possibleimplementation manner of the first aspect, the (N+1)^(th) levelcontroller is further configured to update the status information, whichis included in the message, of the node according to the first messageif the received first message includes status information of the nodebelonging to the (N+1)^(th) level controller, and the node is a boundarynode of the (N+1)^(th) level controller, and send the first message tothe N^(th) level controller to which the (N+1)^(th) level controllerbelongs, and the N^(th) level controller is further configured to updatethe status information of the boundary node of the (N+1)^(th) levelcontroller according to the first message.

With reference to any one of the first aspect and the first to fourthimplementation manners of the first aspect, in a fifth possibleimplementation manner of the first aspect, the (N+1)^(th) levelcontroller is further configured to send a fifth message to the N^(th)level controller to which the (N+1)^(th) level controller belongs if thereceived first message is a data transmission request message andincludes an identifier of a node not belonging to the (N+1)^(th) levelcontroller, where the fifth message includes the identifier of the(N+1)^(th) level controller, an identifier of a target node, and a firsttransmission path, and the first transmission path includes a sourcenode and a first boundary node belonging to a same (N+1)^(th) levelcontroller. The N^(th) level controller is further configured to receivethe fifth message sent by the (N+1)^(th) level controller belonging tothe N^(th) level controller. The N^(th) level controller is furtherconfigured to send a message for acquiring a second transmission path toanother (N+1)^(th) level controller belonging to the N^(th) levelcontroller except the (N+1)^(th) level controller, where the secondtransmission path includes the target node and a second boundary nodebelonging to a same (N+1)^(th) level target controller. The N^(th) levelcontroller is further configured to determine a first backbonetransmission path if the first boundary node and the second boundarynode are connected, where the first backbone transmission path includesthe source node, the first boundary node, the second boundary node, andthe target node, the (N+1)^(th) level controller is further configuredto receive the first backbone transmission path sent by the N^(th) levelcontroller to which the (N+1)^(th) level controller belongs, and the(N+1)^(th) level controller is further configured to determine asub-transmission path of the first backbone transmission path, andinstruct each node in the first sub-transmission path to sequentiallytransmit the data from the source node to the target node.

With reference to the fifth possible implementation manner of the firstaspect, in a sixth possible implementation manner of the first aspect,the N^(th) level controller is further configured to determine a thirdboundary node connected to the first boundary node and a fourth boundarynode connected to the second boundary node if the second boundary nodeand the first boundary node are not connected, and the N^(th) levelcontroller is further configured to determine a second primary backbonetransmission path if the third boundary node and the fourth boundarynode belong to a same (N+1)^(th) level controller, where the secondprimary backbone transmission path includes the source node, the firstboundary node, the second boundary node, the target node, the thirdboundary node, and the fourth boundary node.

With reference to any one of the first aspect and the first to sixthimplementation manners of the first aspect, in a seventh possibleimplementation manner of the first aspect, the N^(th) level controlleris further configured to send a first broadcast message to the(N+1)^(th) level controllers belonging to the N^(th) level controller,where the first broadcast message is used to acquire status informationof the (N+1)^(th) level controllers belonging to the N^(th) levelcontroller and status information of boundary nodes of the (N+1)^(th)level controllers. The (N+1)^(th) level controller is further configuredto return, according to the first broadcast message, status informationof the (N+1)^(th) level controller to the N^(th) level controller towhich the (N+1)^(th) level controller belongs, and the (N+1)^(th) levelcontroller is further configured to send the first broadcast message tothe boundary nodes belonging to the (N+1)^(th) level controller suchthat the boundary nodes return status information of the boundary nodesto the (N+1)^(th) level controller, and send the received statusinformation of the boundary nodes to the N^(th) level controller.

According to a second aspect, an embodiment of the present disclosureprovides an SDN controller configured to perform functions of the N^(th)level controller, the (N+1)^(th) level controller, or the (N−1)^(th)level controller in any one of the first aspect and all implementationmanners of the first aspect.

According to a third aspect, an embodiment of the present disclosureprovides an SDN controlling method, including receiving, by an(N+1)^(th) level controller, a first message sent by a node belonging tothe (N+1)^(th) level controller, and forwarding, by the (N+1)^(th) levelcontroller, the first message to an N^(th) level controller to which the(N+1)^(th) level controller belongs such that the N^(th) levelcontroller performs decision processing on the first message, if thefirst message is a cross-domain message according to status informationof each node that is managed by the (N+1)^(th) level controller and thatbelongs to the (N+1)^(th) level controller, where the first messageincludes an identifier of the node sending the first message, and thecross-domain message includes an identifier of a node belonging toanother (N+1)^(th) level controller.

In a first implementation manner of the third aspect, the forwarding thefirst message to an N^(th) level controller to which the (N+1)^(th)level controller belongs includes adding, by the (N+1)^(th) levelcontroller, an identifier of the (N+1)^(th) level controller to thefirst message, to obtain a second message if the received first messageincludes an identifier of another (N+1)^(th) level controller, andsending, by the (N+1)^(th) level controller, the second message to theN^(th) level controller to which the (N+1)^(th) level controller belongssuch that the N^(th) level controller determines a backbone topology ofthe SDN system according to the second message.

With reference to the first aspect or the first implementation manner ofthe first aspect, in a second implementation manner of the first aspect,the SDN controlling method further includes sending, by the (N+1)^(th)level controller, a fifth message to the N^(th) level controller towhich the (N+1)^(th) level controller belongs if the received firstmessage is a data transmission request message and includes anidentifier of a node not belonging to the (N+1)^(th) level controller,where the fifth message includes the identifier of the (N+1)^(th) levelcontroller, an identifier of a target node, and a first transmissionpath, and the first transmission path includes a source node and a firstboundary node belonging to the same (N+1)^(th) level controller,receiving, by the (N+1)^(th) level controller, a first backbonetransmission path sent by the N^(th) level controller to which the(N+1)^(th) level controller belongs, and determining, by the (N+1)^(th)level controller, a sub-transmission path of the first backbonetransmission path, and instructing each node in the firstsub-transmission path to sequentially transmit the data from the sourcenode to the target node.

With reference to any one of the third aspect and the first and secondpossible implementation manners of the third aspect, in a third possibleimplementation manner of the third aspect, the (N+1)^(th) levelcontroller further receives a first broadcast message sent by the N^(th)level controller to which the (N+1)^(th) level controller belongs, the(N+1)^(th) level controller returns, according to the first broadcastmessage, status information of the (N+1)^(th) level controller to theN^(th) level controller to which the (N+1)^(th) level controllerbelongs, and the (N+1)^(th) level controller sends the first broadcastmessage to boundary nodes belonging to the (N+1)^(th) level controllersuch that the boundary nodes return status information of the boundarynodes to the (N+1)^(th) level controller, and send the received statusinformation of the boundary nodes to the N^(th) level controller.

According to a fourth aspect, an embodiment of the present disclosureprovides an SDN controlling method, including receiving, by an N^(th)level controller, a first message forwarded by an (N+1)^(th) levelcontroller belonging to the N^(th) level controller, and performingdecision processing according to status information of the (N+1)^(th)level controller that is managed by the N^(th) level controller and thatbelongs to the N^(th) level controller and status information ofboundary nodes of the (N+1)^(th) level controller belonging to theN^(th) level controller, where boundary nodes of each (N+1)^(th) levelcontroller include a node, which is connected to a node belonging toanother (N+1)^(th) level controller, of all nodes belonging to the(N+1)^(th) level controller.

In a first possible implementation manner of the fourth aspect, theperforming decision processing includes determining a backbone topologyof the SDN system, determining a backbone transmission path of datatransmission, or updating the status information of the (N+1)^(th) levelcontroller that is managed by the N^(th) level controller and thatbelongs to the N^(th) level controller and the status information of theboundary nodes of the (N+1)^(th) level controller belonging to theN^(th) level controller.

For the SDN system, controller, and controlling method according to theembodiments of the present disclosure, each level of controllerseparately manages status information of a network belonging to a domainof the controller, an upper-level controller manages a lower-levelcontroller and status information of boundary nodes of the lower-levelcontroller, and the lower-level controller manages status information ofnodes belonging to the lower-level controller such that when anycontroller is attacked, networking information cannot be leaked, therebyimproving security of network information.

BRIEF DESCRIPTION OF DRAWINGS

To describe the technical solutions in the embodiments of the presentdisclosure more clearly, the following briefly describes theaccompanying drawings required for describing the embodiments or theprior art. The accompanying drawings in the following description showsome embodiments of the present disclosure, and a person of ordinaryskill in the art may still derive other drawings from these accompanyingdrawings without creative efforts.

FIG. 1 is a schematic structural diagram of Embodiment 1 of an SDNsystem according to an embodiment of the present disclosure;

FIG. 2 is a schematic structural diagram of Embodiment 2 of an SDNsystem according to an embodiment of the present disclosure;

FIG. 3 is a schematic structural diagram of Embodiment 3 of an SDNsystem according to an embodiment of the present disclosure;

FIG. 4 is a schematic structural diagram of Embodiment 4 of an SDNsystem according to an embodiment of the present disclosure;

FIG. 5 is a schematic flowchart of a method for controlling a data routebased on the SDN system shown in FIG. 4 according to an embodiment ofthe present disclosure;

FIG. 6 is a schematic structural diagram of Embodiment 5 of an SDNsystem according to an embodiment of the present disclosure;

FIG. 7 is a schematic flowchart of a method for controlling a data routebased on the SDN system shown in FIG. 6 according to an embodiment ofthe present disclosure;

FIG. 8 is a schematic structural diagram of an embodiment of an SDNcontrol device according to an embodiment of the present disclosure;

FIG. 9 is a schematic flowchart of Embodiment 1 of an SDN controllingmethod according to an embodiment of the present disclosure; and

FIG. 10 is a schematic flowchart of Embodiment 2 of an SDN controllingmethod according to an embodiment of the present disclosure.

DESCRIPTION OF EMBODIMENTS

To make the objectives, technical solutions, and advantages of theembodiments of the present disclosure clearer, the following clearlydescribes the technical solutions in the embodiments of the presentdisclosure with reference to the accompanying drawings in theembodiments of the present disclosure. The described embodiments aresome but not all of the embodiments of the present disclosure. All otherembodiments obtained by a person of ordinary skill in the art based onthe embodiments of the present disclosure without creative efforts shallfall within the protection scope of the present disclosure.

FIG. 1 is a schematic structural diagram of Embodiment 1 of an SDNsystem according to an embodiment of the present disclosure. As shown inFIG. 1, the SDN system includes at least one N^(th) level controller 110and at least two (N+1)^(th) level controllers 121 and 122 directlybelonging to the N^(th) level controller 110, where N is an integergreater than or equal to 1.

The (N+1)^(th) level controller 121 or 122 is configured to receive afirst message sent by a node 141 or 142 belonging to the (N+1)^(th)level controller 121 or 122, and when the first message is across-domain message according to status information of each node thatis managed by the (N+1)^(th) level controller 121 or 122 and thatbelongs to the (N+1)^(th) level controller 121 or 122, forward the firstmessage to the N^(th) level controller 110 to which the (N+1)^(th) levelcontroller 121 or 122 belongs, and the N^(th) level controller 110 isconfigured to receive the first message forwarded by the (N+1)^(th)level controller 121 or 122 belonging to the N^(th) level controller110, and perform decision processing according to status information ofthe (N+1)^(th) level controller that is managed by the N^(th) levelcontroller 110 and that belongs to the N^(th) level controller 110 andstatus information of boundary nodes of the (N+1)^(th) level controllerbelonging to the N^(th) level controller 110. The boundary node 131 or132 of each (N+1)^(th) level controller includes a node, which isconnected to a node belonging to another (N+1)^(th) level controller, ofall nodes belonging to the (N+1)^(th) level controller, the firstmessage includes an identifier of the node sending the first message,and the cross-domain message includes an identifier of the nodebelonging to the other (N+1)^(th) level controller.

For example, an SDN system in FIG. 1 has one N^(th) level controller andonly two (N+1)^(th) level controllers directly belonging to the N^(th)level controller 110. If each (N+1)^(th) level controller separately has10 nodes directly belonging to the (N+1)^(th) level controller, and thetwo (N+1)^(th) level controllers are separately connected to other(N+1)^(th) level controllers using two nodes, that is, each (N+1)^(th)level controller has two boundary nodes. Correspondingly, the N^(th)level controller is configured to manage status information of the fourboundary nodes, and the two (N+1)^(th) level controllers are separatelyconfigured to manage status information of each ten boundary nodesdirectly belonging to the two (N+1)^(th) level controllers.

Belonging includes direct belonging and indirect belonging. The directbelonging refers to that communication can be directly performed betweencontrollers or between a controller and a node without forwarding of athird controller or node. The indirect belonging refers to thatcommunication cannot be directly performed between controllers orbetween a controller and a node, and communication needs to be performedby means of forwarding of another controller. For the (N+1)^(th) levelcontroller, the cross-domain message refers to a message between a nodebelonging to the (N+1)^(th) level controller and a node not belonging tothe (N+1)^(th) level controller. For the ^(Nth) level controller, thecross-domain message refers to a message between an (N+1)^(th) levelcontroller belonging to the N^(th) level controller and an (N+1)^(th)level controller not belonging to the N^(th) level controller. Statusinformation of a node includes connection status information, portstatus information, flow table status information of the node, and anidentifier of the node, and may also include other information that mayindicate a usage state of the node such that a controller may determine,according to the status information of the node, which port of the nodeis currently available, traffic that the available port can carry, andthe like. The identifier (ID) of the node may be an ID of the node orany other identifier that uniquely identifies the node from other nodes.Status information of a controller includes a connection status of thecontroller, load traffic in a management domain of the controller,available load traffic of the controller, and an identifier of thecontroller. The identifier of the controller may be an ID of thecontroller or any other identifier that uniquely identifies thecontroller from other controllers.

The performing, by the N^(th) level controller, decision processingrefers to that the N^(th) level controller processes the first messageaccording to a type of the first message, for example, makes a decisionon a data route, makes a decision on a network topology, or updates thestatus information of the (N+1)^(th) level controller managed by theN^(th) level controller or updates a status message of the boundarynodes of the (N+1)^(th) level controller managed by the N^(th) levelcontroller.

Further, in an SDN, it may be set that each controller connects to acontroller directly belonging to the controller using a southboundinterface, and network information is exchanged using the OPENFLOWprotocol or the non-OPENFLOW protocol.

According to the SDN system provided in this embodiment of the presentdisclosure, each level of controller separately manages statusinformation of a network belonging to a domain of the controller, anupper-level controller manages a lower-level controller and statusinformation of boundary nodes of the lower-level controller, and thelower-level controller manages status information of nodes belonging tothe lower-level controller such that when any controller is attacked,networking information cannot be leaked, thereby improving security ofnetwork information.

Further, in the foregoing SDN system, the (N+1)^(th) level controller isfurther configured to add an identifier of the (N+1)^(th) levelcontroller to the first message, to obtain a second message if thereceived first message includes an identifier of another (N+1)^(th)level controller. The (N+1)^(th) level controller is further configuredto send the second message to the N^(th) level controller to which the(N+1)^(th) level controller belongs, and the N^(th) level controller isfurther configured to receive a second message sent by each (N+1)^(th)level controller belonging to the N^(th) level controller, and determinea backbone topology of the SDN system according to the second message inorder to determine a backbone transmission path of data in the SDNsystem according to the backbone topology.

At an initial stage of network construction, to enable each level ofcontroller to acquire information managed by the controller, each(N+1)^(th) level controller is further configured to send a fourthmessage to each node belonging to the (N+1)^(th) level controller inorder to instruct each node to send the fourth message to a nodeconnected to the node, and receive a first message returned according tothe fourth message by each nodes belonging to the (N+1)^(th) levelcontroller, and if the first message includes an identifier of another(N+1)^(th) level controller, after the identifier of the (N+1)^(th)level controller is added to the first message, directly send a secondmessage to the N^(th) level controller 110 to which the (N+1)^(th) levelcontroller belongs, where the fourth message includes the identifier ofthe (N+1)^(th) level controller and an identifier of a node receivingthe fourth message, the first message includes identifiers of two nodesand an identifier of one (N+1)^(th) level controller, and the secondmessage includes identifiers of two nodes and identifiers of two(N+1)^(th) level controllers, and the N^(th) level controller is furtherconfigured to receive a second message sent by each (N+1)^(th) levelcontroller directly belonging to the N^(th) level controller, anddetermine, according to two second messages including an identifier of asame node and an identifier of a same controller, information aboutconnections between the (N+1)^(th) level controllers belonging to theN^(th) level controller.

Further, in an OPENFLOW network, the foregoing fourth message may befurther a packet_out message. The packet_out message may include anidentifier of a controller sending the packet_out message and anidentifier of a node receiving the packet_out message. In addition, tocontrol a flow direction of the packet_out message, the packet_outmessage may further include an identifier of a port of the nodereceiving the message. In this way, the node receiving the packet_outmessage may send the packet_out message out from a port corresponding tothe identifier of the port. Further, a message carried by the packet_outmassage may be an Link Layer Discovery Protocol (LLDP) message. Inaddition, after receiving a message that is sent by another node andwhose packet_out header is removed, a node may add an identifier of thenode and an identifier of a port of the node to the message, and thensend the message, that is, a first message, to an (N+1)^(th) levelcontroller to which the node directly belongs, where the first messagemay be further a packet_in message.

For example, FIG. 2 is a schematic structural diagram of Embodiment 2 ofan SDN system according to an embodiment of the present disclosure. Asshown in FIG. 2, in the SDN system, there are two (N+1)^(th) levelcontrollers A 123 and B 124 directly belonging to an N^(th) levelcontroller C 111, nodes k 133 and m 134 directly belong to the(N+1)^(th) level controller A 123, nodes n 135 and f 136 directly belongto the (N+1)^(th) level controller B 124, and the nodes m 134 and n 135are connected.

Further, the first (N+1)^(th) level controller A sends a packet_outmessage to a boundary node m of the (N+1)^(th) level controller A, andinstructs the boundary node m to send a message carried in thepacket_out message out using a right port of the boundary node m, forexample, sends an LLDP message out. The boundary node m is connected toa left port of a boundary node n of another (N+1)^(th) level controllerB by means of the right port, and therefore, the boundary node n of theother (N+1)^(th) level controller B receives the LLDP message using theleft port. Then, the boundary node n sends the LLDP message to the(N+1)^(th) level controller B in a form of a packet_in message, andafter receiving the packet_in message sent by the node n, the (N+1)^(th)level controller B determines that the message includes an identifier ofthe (N+1)^(th) level controller A and therefore determines that the noden is a boundary node. After an identifier of the (N+1)^(th) levelcontroller B is added to the packet_in message, the message may be sentto the N^(th) level controller to which the (N+1)^(th) level controllerB directly belongs.

Correspondingly, after receiving first messages sent by both the(N+1)^(th) level controller A and the (N+1)^(th) level controller B, anN^(th) level controller C may determine, according to the two firstmessages including the identifier of the (N+1)^(th) level controller A,the identifier of the (N+1)^(th) level controller B, an identifier ofthe boundary node m, and an identifier of the boundary node n, that the(N+1)^(th) level controller A and the (N+1)^(th) level controller B areconnected by means of the right port of the boundary node m belonging tothe (N+1)^(th) level controller A and the left port of the boundary noden belonging to the (N+1)^(th) level controller B.

If in the SDN system, there is another (N+1)^(th) level controllerbelonging to the N^(th) level controller C, or there are another pair ofboundary nodes connecting the (N+1)^(th) level controller A and the(N+1)^(th) level controller B, the N^(th) level controller may acquireconnection relationships between all (N+1)^(th) level controllersbelonging to the N^(th) level controller in a manner the same as orsimilar to the foregoing manner.

In addition, the (N+1)^(th) level controller is further configured todetermine information about connections of the nodes directly belongingto the (N+1)^(th) level controller if the first message does not includean identifier of another (N+1)^(th) level controller.

For example, if the foregoing (N+1)^(th) level controller A receives apacket_in message sent by the node k directly belonging to the(N+1)^(th) level controller A and finds by means of judgment that thepacket_in message does not include an identifier of another (N+1)^(th)level controller, it may be determined that the node k is a non-boundarynode. Moreover, information about connections between the node k andanother node in a management domain of the (N+1)^(th) level controller Ais determined by means of the packet_in message. An (N+1)^(th) levelcontroller may determine, in a same manner, information aboutconnections of a node directly belonging to the (N+1)^(th) levelcontroller.

In another implementation manner of the foregoing SDN system, the SDNsystem further includes at least one (N−1)^(th) level controller, atleast two N^(th) level controllers belonging to the (N−1)^(th) levelcontroller, and at least four (N+1)^(th) level controllers belonging tothe at least two N^(th) level controllers, where N is an integer greaterthan 1.

The N^(th) level controller is further configured to, if the secondmessage includes an identifier of an (N+1)^(th) level controller notbelonging to the N^(th) level controller, replace the identifier of the(N+1)^(th) level controller in the second message with an identifier ofthe N^(th) level controller, to obtain a third message. The N^(th) levelcontroller is further configured to send the third message to the(N−1)^(th) level controller to which the N^(th) level controllerbelongs, and the (N−1)^(th) level controller is configured to receivethe third message sent by the N^(th) level controller belonging to the(N−1)^(th) level controller, and determine the backbone topology of theSDN system according to the third message in order to determine thebackbone transmission path of the data in the SDN system according tothe backbone topology of the SDN system.

For example, FIG. 3 is a schematic structural diagram of Embodiment 3 ofan SDN system according to an embodiment of the present disclosure. Asshown in FIG. 3, based on the SDN system shown in FIG. 2, the SDN systemfurther includes an N^(th) level controller D 112, an (N−1)^(th) levelcontroller E 101, and an (N+1)^(th) level controller F 125. The N^(th)level controllers C 111 and D 112 directly belong to the (N−1)^(th)level controller E 101, the (N+1)^(th) level controller F 125 directlybelongs to the N^(th) level controller D 112. The (N+1)^(th) levelcontrollers A 123 and B 124 directly belong to the N^(th) levelcontroller C 111, nodes j 137 and p 138 directly belong to the(N+1)^(th) level controller F 125, and nodes f 136 and j 137 areconnected.

Further, after receiving a second message sent by the (N+1)^(th) levelcontroller B 124, the N^(th) level controller C 111 finds by means ofparsing that the second message includes an identifier of the (N+1)^(th)level controller F 125, and the N^(th) level controller C 111 determinesthat the (N+1)^(th) level controller F 125 is not a controller directlybelonging to the N^(th) level controller C 111. Therefore, afteridentifiers of the (N+1)^(th) level controllers F 125 and B 124 in thesecond message are replaced with an identifier of the N^(th) levelcontroller C 111, a third message may be then sent to the (N−1)^(th)level controller E 101 to which the N^(th) level controller C 111directly belongs, where the fourth message includes the identifier ofthe N^(th) level controller C 111, an identifier of the node j, and anidentifier of the node f.

Correspondingly, the (N−1)^(th) level controller E 101 receives fourthmessages sent by the N^(th) level controller C 111 and the N^(th) levelcontroller D 112. Through comparison, it is found that the two fourthmessages have same identifiers the identifier of the node j 137 and theidentifier of the node f 136, and therefore it may be determined thatthe N^(th) level controller C 111 and the N^(th) level controller D 112are connected using the node f 136 and the node j 137.

Further, to facilitate that an N^(th) level controller determinesinformation about connections between (N+1)^(th) level controllersaccording to messages sent by the (N+1)^(th) level controllers, or an(N−1)^(th) level controller determines information about connectionsbetween N^(th) level controllers according to messages sent by theN^(th) level controllers, it may be set that when the (N+1)^(th) levelcontrollers send the messages to the N^(th) level controller, or whenthe N^(th) level controller sends the messages to the (N−1)^(th) levelcontroller, an order of nodes included in the messages meets a presetrule. For example, it is regulated that the first message sequentiallyincludes an identifier of a controller and an identifier of a node. Thesecond message sequentially includes the identifier of the controller,the identifier of the node belonging to the former controller, and anidentifier of a node sending the second message to the controller, thethird message sequentially includes the identifier of the controllersending the first message, the identifier of the node belonging to thecontroller sending the first message, an identifier of a node sendingthe second message, and an identifier of a controller sending the thirdmessage, and so on. It should be noted that, the above descriptions ofan order of identifiers of controllers and identifiers of nodes includedin messages are merely exemplary for explanation. The order of theidentifiers of the foregoing controllers and nodes may also be setaccording to a need as long as controllers receiving messages canrecognize belonging between the nodes and the controllers.

Alternatively, to simplify that all levels of controllers determineinformation about connections between controllers or nodes in managementdomains of the controllers, in another implementation manner of thisembodiment, the (N+1)^(th) level controller is further configured tosend a fourth message to the N^(th) level controller to which the(N+1)^(th) level controller belongs, where the fourth message includesan identifier of a node to which the fourth message is sent and theidentifier of the (N+1)^(th) level controller. The N^(th) levelcontroller is further configured to receive the fourth message sent bythe (N+1)^(th) level controller belonging to the N^(th) levelcontroller, and the N^(th) level controller is further configured todetermine the backbone topology of the SDN system according to thesecond message and the fourth message that include an identifier of asame node in order to determine the backbone transmission path of thedata in the SDN system according to the backbone topology of the SDNsystem.

A network structure shown in FIG. 3 is used as an example. When sendinga fourth message to the node f 136 directly belonging to the (N+1)^(th)level controller B 124, the (N+1)^(th) level controller B 124 maysimultaneously send the message to the N^(th) level controller C 111.After receiving the fourth message including an identifier of the(N+1)^(th) level controller B 124 and the identifier of the node f 136,the N^(th) level controller C 111 replaces the identifier of the(N+1)^(th) level controller B 124 with the identifier of the N^(th)level controller C 111 and sends a modified fourth message to the(N−1)^(th) level controller E 101, that is, the (N−1)^(th) levelcontroller E 101 receives the modified fourth message including theidentifier of the ^(Nth) level controller C 111 and the identifier ofthe node f 136. Meanwhile, the (N−1)^(th) level controller E 101 furtherreceives a fourth message including an identifier of the N^(th) levelcontroller D 112, the identifier of the node f 136, and the identifierof the node j 137, the (N−1)^(th) level controller E 101 may find, bymeans of parsing, two identifiers including a same node f 136, and itmay be determined that the N^(th) level controller C 111 and the N^(th)level controller D 112 are connected by means of the node f 136 and thenode j 137.

It should be noted that, in the above description of determiningconnection relationships between controllers or nodes by a controller ina management domain of the controller, each message may further carry anidentifier of a port of a node such that the controller can determineconnection relationships between the controllers or the nodes in amanagement domain of the controller more precisely. For example, in anetwork architecture shown in FIG. 3, the (N−1)^(th) level controller E101 may determine that the N^(th) level controller C 111 is connected toa left port of the node j 137 of the N^(th) level controller D 112 bymeans of a right port of the node f 136.

In addition, at an initial stage of network construction or when astatus of a node in the SDN system changes, the node in the network maydirectly send a message to a controller to which the node belongs. The(N+1)^(th) level controller is further configured to update the statusinformation, which is included in the message, of the node according tothe first message if the received first message includes statusinformation of the node belonging to the (N+1)^(th) level controller,and the node is a boundary node of the (N+1)^(th) level controller, andsend the first message to the N^(th) level controller to which the(N+1)^(th) level controller belongs, and the N^(th) level controller isfurther configured to update the status information of the boundary nodeof the (N+1)^(th) level controller according to the first message.

An architecture of the SDN system shown in FIG. 3 is used as an example.Assuming that in the network, a failure occurs in the right port, whichis connected to the node n 135, of the node m 134, the node m 134 maysend a first message to the (N+1)^(th) level controller A 123 to whichthe node m directly belongs, where the first message may include theidentifier of the node m 134 and a status of a port of the node m 134,or may further include a flow table status of the node and the like.After receiving the message, the (N+1)^(th) level controller A 123 firstupdates locally stored status information of the node m 134. Inaddition, because the (N+1)^(th) level controller A 123 already knowsthat the node m 134 is a boundary node according to the foregoingprocess, the (N+1)^(th) level controller A 123 may send the firstmessage to the N^(th) level controller C 111, and the N^(th) levelcontroller C 111 may also update the locally stored status informationof the node m 134 according to the first message.

Alternatively, if at an initial stage of network construction, the(N+1)^(th) level controller A 123 receives a first message sent by thenode m 134, the (N+1)^(th) level controller A 123 first stores statusinformation of the node m 134 according to the first message, then sendsa fourth message to the node m 134, determines that the node m is aboundary node according to a first message returned by the node m 134again, and then sends a first message to the N^(th) level controller C111 such that the N^(th) level controller C 111 determines informationabout a connection between the (N+1)^(th) level controllers A 123 and B124 according to the first message, and stores status information of thenode m.

According to the SDN system provided in this embodiment, each level ofcontroller may obtain information about connections between controllersor nodes in a management domain of the controller, and update statusinformation of a node in a network in real time according to the statusinformation sent by the node such that each controller cannot obtainnetworking information, thereby improving security of the network.

In the foregoing network architecture, all levels of controllers maycooperatively complete networking data routing. Further, the (N+1)^(th)level controller is further configured to send a fifth message to theN^(th) level controller to which the (N+1)^(th) level controller belongsif the received first message is a data transmission request message andincludes an identifier of a node not belonging to the (N+1)^(th) levelcontroller, where the fifth message includes the identifier of the(N+1)^(th) level controller, an identifier of a target node, and a firsttransmission path, and the first transmission path includes a sourcenode and a first boundary node belonging to a same (N+1)^(th) levelcontroller. The N^(th) level controller is further configured to receivethe fifth message sent by the (N+1)^(th) level controller belonging tothe N^(th) level controller, and send a message for acquiring a secondtransmission path to another (N+1)^(th) level controller belonging tothe N^(th) level controller except the (N+1)^(th) level controller,where the second transmission path includes the target node and a secondboundary node belonging to a same (N+1)^(th) level target controller.The N^(th) level controller is further configured to determine a firstbackbone transmission path if the first boundary node and the secondboundary node are connected, where the first backbone transmission pathincludes the source node, the first boundary node, the second boundarynode, and the target node, the (N+1)^(th) level controller is furtherconfigured to receive the first backbone transmission path sent by theN^(th) level controller to which the (N+1)^(th) level controllerbelongs, and the (N+1)^(th) level controller is further configured todetermine a sub-transmission path of the first backbone transmissionpath, and instruct each node in the first sub-transmission path tosequentially transmit the data from the source node to the target node.

In this embodiment, when determining a data transmission path, theN^(th) level controller or the (N+1)^(th) level controller needs toconsider that a determined path meets one or a combination of thefollowing conditions, such as being from a source node to a firstboundary node, a path length being the shortest, a delay being theshortest, or a packet loss rate being the lowest.

For example, FIG. 4 is a schematic structural diagram of Embodiment 4 ofan SDN system according to an embodiment of the present disclosure. Asshown in FIG. 4, the architecture is further an (N−1)^(th) levelcontroller 201, an N^(th) level controller 202, and an N^(th) levelcontroller 203, an (N+1)^(th) level controller 204, an (N+1)^(th) levelcontroller 205, an (N+1)^(th) level controller 206, and the like, and afirst switch (SW 1) 207, a second switch (SW 2) 208, a third switch (SW3) 209, a fourth switch (SW 4) 210, a fifth switch (SW 5) 211, a sixthswitch (SW 6) 212, a seventh switch (SW 7) 213, and an eighth switch (SW8) 214. It should be noted that, the architecture may further include an(N+2)^(th) level controller, an (N+3)^(th) level controller, an(N+4)^(th) level controller, an (N−2)^(th) level controller, an(N−3)^(th) level controller, and the like. The architecture may befurther set according to an actual need, and quantities of levels ofcontrollers in the figure are merely for description and setting of thequantities of the levels of controllers is not limited in thisembodiment of the present disclosure.

In FIG. 4, the N^(th) level controller 202 and the N^(th) levelcontroller 203 directly belong to the (N−1)^(th) level controller 201,and the (N+1)^(th) level controller 204 and the (N+1)^(th) levelcontroller 205 directly belong to the N^(th) level controller 202 andindirectly belong to the (N−1)^(th) level controller 201, and the(N+1)^(th) level controller 206 directly belongs to the N^(th) levelcontroller 203 and indirectly belongs to the (N−1)^(th) level controller201. The SW 1 207, the SW 2 208, and the SW 3 209 directly belong to the(N+1)^(th) level controller 204 and indirectly belong to the N^(th)level controller 202 and the (N−1)^(th) level controller 201. The SW 4210, the SW 5 211, and the SW 6 212 directly belong to the (N+1)^(th)level controller 205 and indirectly belong to the N^(th) levelcontroller 202 and the (N−1)^(th) level controller 201, and the SW 7 213and the SW 8 214 directly belong to the (N+1)^(th) level controller 206and indirectly belong to the N^(th) level controller 203 and the(N−1)^(th) level controller 201.

For the (N−1)^(th) level controller 201, boundary nodes are the SW 1 207and the SW 8 214. For the N^(th) level controller 202, boundary nodesare the SW 1 207 and the SW 6 212. For the N^(th) level controller 203,boundary nodes are the SW 7 213 and the SW 8 214. For the (N+1)^(th)level controller 204, boundary nodes are the SW 1 207 and the SW 3 209.For the (N+1)^(th) level controller 205, boundary nodes are the SW 4 210and the SW 6 212. For the (N+1)^(th) level controller 206, boundarynodes are the SW 7 213 and the SW 8 214.

FIG. 5 is a schematic flowchart of determining a data route by acontroller based on the SDN system shown in FIG. 4. As shown in FIG. 5,assuming that in the SDN system, there is data needing to be transmittedfrom the second switch 208 to the fifth switch 211, a process in whichcontrollers cooperatively determine a data route is as follows.

Step S501: The second switch 208 sends a data transmission request tothe (N+1)^(th) level controller 204.

A target node for data transmission is the fifth switch 211.

Step S502: The (N+1)^(th) level controller 204 determines that the fifthswitch 211 does not directly belong to and is not directly managed bythe (N+1)^(th) level controller 204 and therefore sends the datatransmission request to the N^(th) level controller 202.

When the (N+1)^(th) level controller 204 sends the data transmissionrequest, the foregoing data transmission request includes statusinformation of the second switch 208, an identifier of the fifth switch211, an identifier of the (N+1)^(th) level controller 204, and a firsttransmission path composed of the second switch 208 and each boundaryswitch belonging to the (N+1)^(th) level controller 204. Further, thefirst transmission path includes a path of the second switch 208→thethird switch 209 and a path of the second switch 208→the first switch207. It should be noted that, if in the SDN system shown in FIG. 4,there is further another switch between the second switch 208 and thethird switch 209 or the first switch 207, a first transmission path ofsending from the (N+1)^(th) level controller 204 to the N^(th) levelcontroller 202 is still the foregoing path, and does not includeinformation about any intermediate switch in order to ensure that theN^(th) level controller 202 cannot obtain information about connectionsbetween nodes directly belonging to the (N+1)^(th) level controller 204,that is, path information sent by each level of controller to acontroller to which each level of controller directly belongs in thepresent disclosure merely indicates path costs.

It should be noted that, “→” in the embodiments of the presentdisclosure indicates that there is a connection relationship betweennodes, but is not intended to limit a direction.

Step S503: The N^(th) level controller 202 sends a path acquisitionmessage to the (N+1)^(th) level controller 205, to acquire a secondtransmission path that includes a destination node, that is, the fifthswitch 211.

Step S504: The N^(th) level controller 202 receives the secondtransmission path sent by the (N+1)^(th) level target controller 205.

The second transmission path includes the fifth switch 211→the fourthswitch 210 and the fifth switch 211→the sixth switch 212.

Same as the foregoing first transmission path, the second transmissionpath herein also indicates that the target node, that is, the fifthswitch 211 and boundary nodes belonging to the (N+1)^(th) level targetcontroller 205 are reachable, but does not indicate that the fifthswitch 211 and each boundary node belonging to the (N+1)^(th) leveltarget controller 205 are in a direct connection relationship.

Step S505: The N^(th) level controller 202 determines that the fourthswitch 210 in the second transmission path and the third switch 209 in afirst transmission path are connected and determines a first backbonetransmission path.

The first backbone transmission path is the second switch 208→the thirdswitch 209→the fourth switch 210→the fifth switch 211.

It should be noted that, if in the SDN system in FIG. 4, for the firsttransmission path and the second transmission path, in addition to thefourth switch 210 and the third switch 209 for connection, there isfurther other nodes for connection of the first transmission path andthe second transmission path, when determining the first backbonetransmission path, the N^(th) level controller 202 needs to compare pathlengths, delays, or packet loss rates of all paths that are composed ofthe first transmission path and the second transmission paths and thatenable that the source node and the destination node are reachable, andselects, from the paths, a first backbone transmission path that has ashortest path length, a shortest delay, or a lowest packet loss rate andthat is composed of the first transmission path and the secondtransmission path.

In a possible implementation manner of this embodiment, the N^(th) levelcontroller is further configured to determine a third boundary nodeconnected to the first boundary node and a fourth boundary nodeconnected to the second boundary node if the second boundary node andthe first boundary node are not connected, and the N^(th) levelcontroller is further configured to, if the third boundary node and thefourth boundary node belong to a same (N+1)^(th) level controller,determine a second primary backbone transmission path, where the secondprimary backbone transmission path includes the source node, the firstboundary node, the second boundary node, the target node, the thirdboundary node, and the fourth boundary node.

That is, if there is no node directly connecting the first transmissionpath and the second transmission path, the N^(th) level controller needsto send a path acquisition message to another (N+1)^(th) levelcontroller belonging to the N^(th) level controller to acquire a pathconnected to the first transmission path and the second transmissionpath until a reachable transmission path from the source node to thetarget node is finally acquired.

Step S506: The N^(th) level controller 202 respectively sends adetermined target first transmission path and a determined target secondtransmission path to the (N+1)^(th) level source controller 204 and the(N+1)^(th) level target controller 205.

Further, the N^(th) level controller 202 sends the second switch 208→thethird switch 209 to the (N+1)^(th) level source controller 204 and sendsthe fourth switch 210→the fifth switch 211 to the (N+1)^(th) leveltarget controller 205.

Step S507: The (N+1)^(th) level source controller 204 determines asub-transmission path of the target first transmission path.

The sub-transmission path of the target first transmission path is thesecond switch 208→the third switch 209.

Step S508: The (N+1)^(th) level target controller 205 determines asub-transmission path of the target second transmission path.

The sub-transmission path of the target second transmission path is thefourth switch 210→the fifth switch 211.

Because based on the network in FIG. 4, the second switch 208 and thethird switch 209 in the first transmission path and the fourth switch210 and the fifth switch 211 in the second transmission path all aredirectly connected switches, both the first transmission path and thesecond transmission path may constitute a specific transmission pathfrom a source node to a target node. If the second switch 208 and thethird switch 209 are reachable by means of several other switches, andthe fourth switch 210 and the fifth switch 211 are reachable by means ofseveral other switches, the (N+1)^(th) level source controller 204 needsto determine, according to information about connections betweenswitches in a management domain of the (N+1)^(th) level sourcecontroller 204 and according to a principle that a length of a path fromthe second switch 208 to the third switch 209 is the shortest, a delayfrom the second switch 208 to the third switch 209 is the shortest, or apacket loss rate from the second switch 208 to the third switch 209 isthe lowest, which switches data needs to pass by when the data istransmitted from the second switch 208 to the third switch 209, and the(N+1)^(th) level target controller 205 needs to determine, according toinformation about connections between switches in a management domain ofthe (N+1)^(th) level target controller 205 and according to a principlethat a length of a path from the fourth switch 210 to the fifth switch211 is the shortest, a delay from the fourth switch 210 to the fifthswitch 211 is the shortest, or a packet loss rate from the fourth switch210 to the fifth switch 211 is the lowest, which switches data needs topass by when the data is transmitted from the fourth switch 210 to thetarget switch 211.

Correspondingly, the data may be sequentially transmitted from thesecond switch 208 to the target node, that is, the fifth switch 211according to the second switch 208→the third switch 209→the fourthswitch 210→the fifth switch 211. Further, the foregoing transmissionpath further includes port information of each switch, for example, thesecond switch 208 (a right port)→the third switch 209 (a left port), andthe third switch 209 (a right port)→the fourth switch 210 (a left port).The above descriptions of ports of each switch are merely exemplary andare not limited herein.

According to the data transmission controlling method provided in thisembodiment, when a data transmission path is determined, a controllernot directly managing nodes can only determine a backbone transmissionpath according to a transmission path acquired by each controllerdirectly belonging to the controller not directly managing nodes. Eachsub-transmission path included in the backbone transmission path isdetermined by a controller to which each node in the backbonetransmission path directly belongs. The controllers cooperativelycomplete data transmission control, and none of the controllers canacquire networking information, and the controllers can only acquireinformation about boundary nodes in management domains of thecontrollers. Therefore, even if one or more controllers are maliciouslyattacked, networking information is not leaked, thereby improvingsecurity of the networking information.

In another possible implementation manner of the foregoing embodiment,the foregoing SDN system further includes at least two (N+2)^(th) levelcontrollers, where the two (N+2)^(th) level controllers respectivelydirectly belong to the (N+1)^(th) level source controller and the(N+1)^(th) level target controller. The (N+1)^(th) level sourcecontroller and the (N+1)^(th) level target controller are furtherconfigured to if it is determined that each node in a first primarybackbone transmission path is an indirect belonging node, separatelydetermine a secondary backbone transmission path of the target firsttransmission path and the target second transmission path in the firstprimary backbone transmission path according to a preset rule, and sendthe secondary backbone transmission path to each (N+2)^(th) levelcontroller to which each node in the secondary backbone transmissionpath directly belongs such that when determining that the each node inthe secondary backbone transmission path is a direct belonging nodeaccording to the preset rule, each (N+2)^(th) level controllerseparately determines a secondary-sub-transmission path of the secondarybackbone transmission path and instructs each node in eachsecondary-sub-transmission path to sequentially transmit data from asource node to a target node.

FIG. 6 is a schematic structural diagram of Embodiment 5 of an SDNsystem according to an embodiment of the present disclosure. As shown inFIG. 6, based on FIG. 4, the network further includes an (N+1)^(th)level controller 401, an (N+2)^(th) level controller 402, an (N+2)^(th)level controller 403, an (N+2)^(th) level controller 404, an (N+2)^(th)level controller 405, an (N+2)^(th) level controller 406, an (N+2)^(th)level controller 407, a ninth switch (SW 9) 408, a tenth switch (SW 10)409, an eleventh switch (SW 11) 410, and a twelfth switch (SW 12) 411.Further, the (N+1)^(th) level controller 204, the (N+1)^(th) levelcontroller 205, and the (N+1)^(th) level controller 206 directly belongto the N^(th) level controller 202, the (N+1)^(th) level controller 401directly belongs to the N^(th) level controller 203, the (N+2)^(th)level controller 402 directly belongs to the (N+1)^(th) level controller204 and indirectly belongs to the N^(th) level controller 202 and the(N−1)^(th) level controller 201, the (N+2)^(th) level controller 403 andthe (N+2)^(th) level controller 404 directly belong to the (N+1)^(th)level controller 205 and indirectly belong to the N^(th) levelcontroller 202 and the (N−1)^(th) level controller 201, the (N+2)^(th)level controller 405 directly belongs to the (N+1)^(th) level controller206 and indirectly belongs to the N^(th) level controller 202 and the(N−1)^(th) level controller 201, the (N+2)^(th) level controller 406 andthe (N+2)^(th) level controller 407 directly belong to the (N+1)^(th)level controller 401 and indirectly belong to the N^(th) levelcontroller 203 and the (N−1)^(th) level controller 201, the first switch207 to the third switch 209 directly belong to the (N+2)^(th) levelcontroller 402 and indirectly belong to the (N+1)^(th) level controller204, the N^(th) level controller 202, and the (N−1)^(th) levelcontroller 201, the fourth switch 210 directly belongs to the (N+2)^(th)level controller 403 and indirectly belongs to the (N+1)^(th) levelcontroller 205, the N^(th) level switch 202, and the (N−1)^(th) levelswitch 201, the fifth switch 211 and the sixth switch 212 directlybelong to the (N+2)^(th) level controller 404 and indirectly belong tothe (N+1)^(th) level controller 205, the N^(th) level controller 202,and the (N−1)^(th) level controller 201, and the like.

FIG. 7 is a schematic flowchart of determining a data route by acontroller based on the SDN system shown in FIG. 6. As shown in FIG. 7,assuming that there is data needing to be transmitted from the secondswitch 208 to the eighth switch 214, a process in which each controllerin the network determines a data route is as follows.

Step S701: The second switch 208 sends a data transmission request tothe (N+2)^(th) level controller 402.

The data transmission request includes an identifier of a target node,that is, the eighth switch 214.

Step S702: The (N+2)^(th) level controller 402 determines that theeighth switch 214 does not directly belong to and is not directlymanaged by the (N+2)^(th) level controller 402 and sends the datatransmission request to the (N+1)^(th) level controller 204.

The data transmission request includes an identifier of the (N+2)^(th)level controller 402, an identifier of the target node, that is, theeighth switch 214, and the first transmission path, that is, the secondswitch 208→the third switch 209, and the second switch 208→the firstswitch 207.

Step S703: The (N+1)^(th) level controller 204 determines that besidesthe (N+2)^(th) level source controller, there is no other (N+2)^(th)level controller in a management domain of the (N+1)^(th) levelcontroller 204 and sends the data transmission request to the N^(th)level controller 202.

The data transmission request includes an identifier of the (N+2)^(th)level controller 402, the identifier of the target node, that is, theeighth switch 214, and the first transmission path, that is, the secondswitch 208→the third switch 209 and the second switch 208→the firstswitch 207.

If the (N+1)^(th) level controller 204 determines that besides an(N+2)^(th) level source controller, there is another (N+2)^(th) levelcontroller in a management domain of the (N+1)^(th) level controller204, the (N+1)^(th) level controller 204 needs to send a pathacquisition message to the other (N+2)^(th) level controller in themanagement domain of the (N+1)^(th) level controller 204. The pathacquisition message is the same as the path acquisition message in FIG.5 and is used to acquire a transmission path from a destination node toa boundary node that belongs to a same level of controller with thedestination node. If the (N+1)^(th) level controller 204 receives,within a preset time, a second transmission path that includes thedestination node and that is sent by an (N+2)^(th) level controller,each controller may determine a data route according to a process of theforegoing steps S503 to S508.

Further, all levels of controllers may acquire status information ofcontrollers or nodes in management domains of the controllers in abroadcast form. For example, the N^(th) level controller is furtherconfigured to send a first broadcast message to the (N+1)^(th) levelcontrollers belonging to the N^(th) level controller, where the firstbroadcast message is used to acquire status information of the(N+1)^(th) level controllers belonging to the N^(th) level controllerand status information of boundary nodes of the (N+1)^(th) levelcontrollers. The (N+1)^(th) level controller is further configured toreturn, according to the first broadcast message, status information ofthe (N+1)^(th) level controller to the N^(th) level controller to whichthe (N+1)^(th) level controller belongs, and the (N+1)^(th) levelcontroller is further configured to send the first broadcast message tothe boundary nodes belonging to the (N+1)^(th) level controller suchthat the boundary nodes return status information of the boundary nodesto the (N+1)^(th) level controller, and send the received statusinformation of the boundary nodes to the N^(th) level controller.

The status information of each controller may include information abouta backbone transmission path in a management domain of each controller,information about a path length between boundary nodes, bandwidthmargins of the controllers, or loads of the controllers. The statusinformation of the node may include a port status and a flow tablestatus of the node.

Step S704: The N^(th) level controller 202 sends a third broadcastmessage to another (N+1)^(th) level controller in a management domain ofthe N^(th) level controller 202.

The third broadcast message is similar to the foregoing first broadcastmessage and is used to acquire information about connections between thetarget node and boundary nodes belonging to a same (N+1)^(th) levelcontroller as the target node.

Step S705: The (N+1)^(th) level controller 205 and the (N+1)^(th) levelcontroller 206 separately send a fourth broadcast message to the(N+2)^(th) level controllers in management domains of the (N+1)^(th)level controller 205 and the (N+1)^(th) level controller 206.

The fourth broadcast message is similar to the foregoing third broadcastmessage and the foregoing first broadcast message, and is used toacquire information about connections between the target node andboundary nodes belonging to a same (N+2)^(th) level controller as thetarget node.

Step S706: The (N+2)^(th) level controller 405 sends a secondtransmission path to the (N+1)^(th) level controller 206.

Further, after receiving the fourth broadcast message, the (N+2)^(th)level controller 405 may know through search that the target node, thatis, the eighth switch 214 is a node directly belonging to the (N+2)^(th)level controller 405, and information about connections between theeighth switch 214 and boundary nodes in a management domain of the(N+2)^(th) level controller 405 is the eighth switch 214→the ninthswitch 408 and the eighth switch 214→the seventh switch 213. Therefore,a determined second transmission path is sent to the (N+1)^(th) levelcontroller 206. It should be noted that, in FIG. 6, whether there isfurther another switch from the eighth switch 214 to the ninth switch408 or the seventh switch 213 does not affect sending of the secondtransmission path by the (N+2)^(th) level controller 405 to the(N+1)^(th) level controller 206, that is, the second transmission pathmerely indicates that the eighth switch 214 to the ninth switch 408 orthe seventh switch 213 is reachable in terms of path, and does notindicate a connection relationship.

Step S707: The (N+1)^(th) level controller 206 sends the secondtransmission path to the N^(th) level controller 202.

According to the SDN system provided in this embodiment of the presentdisclosure, the foregoing N^(th) level controller is further configuredto determine, according to status information of a boundary node of the(N+1)^(th) level controller that is managed by and that directly belongsto the N^(th) level controller, each third boundary node connected toeach first boundary node and each fourth boundary node connected to eachsecond boundary node when no second boundary node in each secondtransmission path is connected to the first boundary node in each firsttransmission path, and determine a second primary backbone transmissionpath, where the second primary backbone transmission path includes thesource node, the first boundary node, the second boundary node, thetarget node, and the third boundary node and the fourth boundary nodethat meet a preset condition if the third boundary node and the fourthboundary node belong to a same (N+1)^(th) level controller.

Step S708: The N^(th) level controller 202 determines a second backbonetransmission path.

Further, after the ^(Nth) level controller 202 receives the secondtransmission path, it may be known according to information aboutconnections between the (N+1)^(th) level controllers managed by the^(Nth) level controller 202 that boundary nodes in the firsttransmission path and the second transmission path are not connected,the third switch 209 in the first transmission path is connected to thefourth switch 210, the seventh switch 213 and the sixth switch 212 areconnected, and both the fourth switch 210 and the sixth switch 212belong to the (N+1)^(th) level controller 205, and therefore, it isdetermined that a second backbone transmission path is the second switch208→the third switch 209→the fourth switch 210→the sixth switch 212→theseventh switch 213→the eighth switch 214.

Step S709: The N^(th) level controller 202 separately sends a targettransmission path belonging to each (N+1)^(th) level controller to the(N+1)^(th) level controller.

Further, the N^(th) level controller 202 sends information about thesecond switch 208→the third switch 209 to the (N+1)^(th) levelcontroller 204, sends information about the fourth switch 210→the sixthswitch 212 to the (N+1)^(th) level controller 205, and sends informationabout the seventh switch 213→the eighth switch 214 to the (N+1)^(th)level controller 206.

After each (N+1)^(th) level controller receives path information,because each node is not a node directly belonging to the controller,the (N+1)^(th) level source controller and the (N+1)^(th) level targetcontroller are further configured to determine, separately according apreset rule, secondary backbone transmission paths of a target firsttransmission path and a target second transmission path in the firstprimary backbone transmission path if each node in the first primarybackbone transmission path is an indirect belonging node, and send thesecondary backbone transmission paths to each (N+2)^(th) levelcontroller to which each node in the secondary backbone transmissionpaths directly belongs such that when determining that each node in thesecondary backbone transmission path is a direct belonging nodeaccording to the preset rule, each (N+2)^(th) level controllerseparately determines each secondary sub-transmission path of thesecondary backbone transmission paths, and instruct each node in eachsecondary sub-transmission path to sequentially transmit the data fromthe source node to the target node.

Step S710: Each (N+1)^(th) level controller separately determines asecondary backbone transmission path of a target transmission pathbelonging to the (N+1)^(th) level controller.

The (N+1)^(th) level controller 204 determines, according to informationabout connections between (N+2)^(th) level controllers managed by the(N+1)^(th) level controller 204, that a secondary backbone transmissionpath, which is in a management domain of the (N+1)^(th) level controller204, of the second switch 208→the third switch 209 is the second switch208→the third switch 209. Similarly, the (N+1)^(th) level controller 205determines that a secondary backbone transmission path, in a managementdomain of the (N+1)^(th) level controller 205, of the fourth switch210→the sixth switch 212 is the fourth switch 210→the fifth switch211→the sixth switch 212.

Step S711: Each (N+1)^(th) level controller sends each secondarybackbone transmission path to each (N+2)^(th) level controller directlybelonging to the (N+1)^(th) level controller.

The (N+1)^(th) level controller 204 sends the second switch 208→thethird switch 209 to the (N+2)^(th) level controller 402, and the(N+1)^(th) level controller 205 sends the fourth switch 210 to the(N+2)^(th) level controller 403 and the fifth switch 211→the sixthswitch 212 to the (N+2)^(th) level controller 402.

Step S712: Each (N+2)^(th) level controller determines asub-transmission path of each secondary backbone transmission path.

The (N+2)^(th) level controller 402 determines that a sub-transmissionpath of the second switch 208→the third switch 209 is the second switch208→the third switch 209, and controls each switch to send data from thesource node, that is, the second switch 208 to the target node, that is,the eighth switch 214.

According to the method of data routing provided in this embodiment,when a data transmission path is determined, a controller not directlymanaging a node can acquire a backbone transmission path between nodesbelonging to a domain of the controller, where a secondary backbonetransmission path included in the backbone transmission path and eachsub-transmission paths included in each secondary backbone transmissionpath are separately sequentially obtained by different levels ofcontrollers according to information about nodes in management domainsof the controllers. The controllers cooperatively complete datatransmission control, and none of the controllers can acquire networkinginformation, and the controllers can only acquire information aboutboundary nodes in management domains of the controllers. Therefore, evenif one or more controllers are maliciously attacked, networkinginformation is not leaked, thereby improving security of the networkinginformation.

FIG. 8 is a schematic structural diagram of an embodiment of an SDNcontrol device according to an embodiment of the present disclosure. Asshown in FIG. 8, the SDN control device 800 includes a processor 810, amemory 820, and at least one communications port 830. The communicationsport 830 is configured to communicate with an external device. Thememory 820 is used to store a computer program instruction. Theprocessor 810 is coupled with the memory and is configured to invoke thecomputer program instruction stored in the memory 820 to perform afunction of an N^(th) level controller, an (N+1)^(th) level controller,an (N−1)^(th) level controller, or an (N+2)^(th) level controller in theSDN system.

A function of the processor 810 of the SDN system control deviceprovided in this embodiment may be set according to a level on which thecontroller is in the SDN system. All controllers constituting the SDNsystem may acquire information about nodes in management domains of thecontrollers, and cooperatively complete data transmission control of theSDN system according to managed information. For the function of theprocessor 810 in the SDN system control device, reference may be made tospecific descriptions of the foregoing embodiments, and details are notdescribed herein again.

According to the SDN system control device provided in this embodiment,different SDN system control devices separately manage information aboutdifferent controllers or nodes according to positions of the SDN systemcontrol devices in an SDN system, and none of the SDN system controldevices can obtain networking information. Therefore, even if one ormore controllers are attacked, networking information is not leaked,thereby improving security of the networking information.

FIG. 9 is a schematic flowchart of Embodiment 1 of an SDN controllingmethod according to an embodiment of the present disclosure. As shown inFIG. 9, the SDN controlling method includes the following steps.

Step S910: An (N+1)^(th) level controller receives a first message sentby a node belonging to the (N+1)^(th) level controller.

Step S920: If the first message is a cross-domain message according tostatus information of each node that is managed by the (N+1)^(th) levelcontroller and that belongs to the (N+1)^(th) level controller, the(N+1)^(th) level controller forwards the first message to an N^(th)level controller to which the (N+1)^(th) level controller belongs suchthat the N^(th) level controller performs decision processing on thefirst message.

The first message includes an identifier of the node sending the firstmessage, and the cross-domain message includes an identifier of a nodebelonging to another (N+1)^(th) level controller.

In one possible implementation manner of this embodiment, the forwardingthe first message to an N^(th) level controller to which the (N+1)^(th)level controller belongs includes if it is determined that the receivedfirst message includes an identifier of another (N+1)^(th) levelcontroller, adding, by the (N+1)^(th) level controller, an identifier ofthe (N+1)^(th) level controller to the first message, to obtain a secondmessage, and sending, by the (N+1)^(th) level controller, the secondmessage to the N^(th) level controller to which the (N+1)^(th) levelcontroller belongs such that the N^(th) level controller determines abackbone topology of the SDN system according to the second message.

In another possible implementation manner of this embodiment, the methodfurther includes if it is determined that the received first message isa data transmission request message and includes an identifier of a nodenot belonging to the (N+1)^(th) level controller, sending, by the(N+1)^(th) level controller, a fifth message to the N^(th) levelcontroller to which the (N+1)^(th) level controller belongs, where thefifth message includes the identifier of the (N+1)^(th) levelcontroller, an identifier of a target node, and a first transmissionpath, and the first transmission path includes a source node and a firstboundary node belonging to the same (N+1)^(th) level controller,receiving, by the (N+1)^(th) level controller, a first backbonetransmission path sent by the N^(th) level controller to which the(N+1)^(th) level controller belongs, and determining, by the (N+1)^(th)level controller, a sub-transmission path of the first backbonetransmission path, and instructing each node in the firstsub-transmission path to sequentially transmit the data from the sourcenode to the target node.

Alternatively, the SDN controlling method provided in the foregoingembodiment further includes further receiving, by the (N+1)^(th) levelcontroller, a first broadcast message sent by the N^(th) levelcontroller to which the (N+1)^(th) level controller belongs, returning,by the (N+1)^(th) level controller according to the first broadcastmessage, status information of the (N+1)^(th) level controller to theN^(th) level controller to which the (N+1)^(th) level controllerbelongs, and sending, by the (N+1)^(th) level controller, the firstbroadcast message to boundary nodes belonging to the (N+1)^(th) levelcontroller such that the boundary nodes return status information of theboundary nodes to the (N+1)^(th) level controller, and send the receivedstatus information of the boundary nodes to the N^(th) level controller.

According to the SDN controlling method provided in this embodiment, fordetailed explanations and descriptions of processing procedures of an(N+1)^(th) level controller, reference may be made to explanations anddescriptions of the foregoing embodiments and related embodiments of theSDN system in the present disclosure, and details are not describedherein again.

According to the SDN controlling method provided in this embodiment ofthe present disclosure, an (N+1)^(th) level controller manages statusinformation of only each node belonging to the (N+1)^(th) levelcontroller, and completes, by cooperating with an N^(th) levelcontroller and according to the status information of each node managedby the (N+1)^(th) level controller, network control such as data routingand topology discovery of a network such that when any controller isattacked, networking information cannot be leaked, thereby improvingsecurity of network information.

FIG. 10 is a schematic flowchart of Embodiment 2 of an SDN controllingmethod according to an embodiment of the present disclosure. As shown inFIG. 10, the SDN controlling method includes the following step.

Step S101: An N^(th) level controller receives a first message forwardedby an (N+1)^(th) level controller belonging to the N^(th) levelcontroller, and performs decision processing according to statusinformation of the (N+1)^(th) level controller that is managed by theN^(th) level controller and that belongs to the N^(th) level controllerand status information of boundary nodes of the (N+1)^(th) levelcontroller belonging to the ^(Nth) level controller.

Boundary nodes of each (N+1)^(th) level controller include a node, whichis connected to a node belonging to another (N+1)^(th) level controller,of all nodes belonging to the (N+1)^(th) level controller.

The performing decision processing includes determining a backbonetopology of the SDN system, determining a backbone transmission path ofdata transmission, or updating the status information of the (N+1)^(th)level controller that is managed by the N^(th) level controller and thatbelongs to the N^(th) level controller and the status information of theboundary nodes of the (N+1)^(th) level controller belonging to theN^(th) level controller.

According to the SDN controlling method provided in this embodiment, fordetailed explanations and descriptions of processing procedures of anN^(th) level controller, reference may be made to explanations anddescriptions of the foregoing embodiments and related embodiments of theSDN system in the present disclosure, and details are not describedherein again.

According to the SDN controlling method provided in the embodiments ofthe present disclosure, an N^(th) level controller manages only each(N+1)^(th) level controller belonging to the N^(th) level controller andstatus information of each boundary node of the (N+1)^(th) levelcontroller belonging to the N^(th) level controller, and completes, bycooperating with the (N+1)^(th) level controller and according to thestatus information managed by the N^(th) level controller, networkcontrol such as data routing and topology discovery of a network suchthat when any controller is attacked, networking information cannot beleaked, thereby improving security of network information.

A person of ordinary skill in the art may understand that all or some ofthe steps of the method embodiments may be implemented by a programinstructing relevant hardware. The program may be stored in a computerreadable storage medium. When the program runs, the steps of the methodembodiments are performed. The foregoing storage medium includes anymedium that can store program code, such as a read-only memory (ROM), arandom-access memory (RAM), a magnetic disk, or an optical disc.

Finally, it should be noted that the foregoing embodiments are merelyintended for describing the technical solutions of the presentdisclosure but not for limiting the present disclosure. Although thepresent disclosure is described in detail with reference to theforegoing embodiments, persons of ordinary skill in the art shouldunderstand that they may still make modifications to the technicalsolutions described in the foregoing embodiments or make equivalentreplacements to some technical features thereof, without departing fromthe spirit and scope of the technical solutions of the embodiments ofthe present disclosure.

What is claimed is:
 1. A software defined network (SDN) system,comprising at least one N^(th) level controller and at least two(N+1)^(th) level controllers, wherein each (N+1)^(th) level controllerbelongs to a N^(th) level controller, wherein N is an integer greaterthan or equal to 1, wherein a first (N+1)^(th) level controller isconfigured to: receive a first message from a node belonging to thefirst (N+1)^(th) level controller, wherein the first message comprisesan identifier of the node sending the first message; send a secondmessage to a first N^(th) level controller to which the first (N+1)^(th)level controller belongs in response to determining that the firstmessage is a cross-domain message comprising an identifier of a nodebelonging to a second (N+1)^(th) level controller; wherein the firstN^(th) level controller is configured to: receive the second messagefrom the first (N+1)^(th) level controller; and perform decisionprocessing based on status information of the first (N+1)^(th) levelcontroller and status information of boundary nodes of the first(N+1)^(th) level controller in response to the second message, wherein aboundary node of the first (N+1)^(th) level controller belongs to thefirst (N+1)^(th) level controller and couples to a node belonging to adifferent (N+1)^(th) level controller.
 2. The SDN system of claim 1,wherein the first (N+1)^(th) level controller is further configured to:add an identifier of the first (N+1)^(th) level controller to the firstmessage to obtain a third message in response to the received firstmessage comprising an identifier of a third (N+1)^(th) level controller;and send the third message to the first N^(th) level controller, andwherein the first N^(th) level controller is further configured to:receive a plurality of third messages from each (N+1)^(th) levelcontroller belonging to the first N^(th) level controller; and determinea backbone topology of the SDN system based on the plurality of thirdmessages to determine a backbone transmission path of data in the SDNsystem based on the backbone topology.
 3. The SDN system of claim 2,further comprising a (N−1)^(th) level controller, wherein the firstN^(th) level controller belongs to the (N−1)^(th) level controller,wherein N is an integer greater than 1, wherein the first N^(th) levelcontroller is further configured to: replace the identifier of the third(N+1)^(th) level controller in the third message with an identifier ofthe first N^(th) level controller to obtain a fourth message in responseto the third message comprising the identifier of the third (N+1)^(th)level controller not belonging to the first N^(th) level controller; andsend the fourth message to the (N−1)^(th) level controller, and whereinthe (N−1)^(th) level controller is configured to: receive the fourthmessage from the first N^(th) level controller; and determine thebackbone topology of the SDN system based on the fourth message todetermine the backbone transmission path of the data in the SDN systembased on the backbone topology of the SDN system.
 4. The SDN system ofclaim 2, wherein the first (N+1)^(th) level controller is furtherconfigured to separately send a fifth message to the first N^(th) levelcontroller and a node belonging to the first (N+1)^(th) levelcontroller, wherein the fifth message comprises an identifier of thenode to which the fifth message is sent and the identifier of the first(N+1)^(th) level controller, and wherein the first N^(th) levelcontroller is further configured to: receive the fifth message from thefirst (N+1)^(th) level controller; determine the backbone topology ofthe SDN system based on the third message and the fifth message thatcomprise an identifier of a same node; and determine the backbonetransmission path of the data in the SDN system based on the backbonetopology of the SDN system.
 5. The SDN system of claim 1, wherein thefirst (N+1)^(th) level controller is further configured to: update thestatus information of the node based on the first message, wherein thestatus information is comprised in the first message; and send the firstmessage to the first N^(th) level controller in response to the receivedfirst message comprising status information of the node, wherein thenode is a boundary node of the first (N+1)^(th) level controller, andwherein the first N^(th) level controller is further configured toupdate the status information of the boundary node of the first(N+1)^(th) level controller based on the first message.
 6. The SDNsystem of claim 1, wherein the first (N+1)^(th) level controller isfurther configured to send a sixth message to the first N^(th) levelcontroller in response to the received first message being a datatransmission request message and comprising an identifier of a node notbelonging to the first (N+1)^(th) level controller, wherein the sixthmessage comprises each of an identifier of the first (N+1)^(th) levelcontroller, an identifier of a target node, and a first transmissionpath, wherein the first transmission path comprises a source node and afirst boundary node belonging to the first (N+1)^(th) level controller,wherein the first Nth level controller is further configured to: receivethe sixth message from the first (N+1)^(th) level controller; send amessage for acquiring a second transmission path to a third (N+1)^(th)level controller belonging to the first N^(th) level controller, whereinthe second transmission path comprises the target node and a secondboundary node belonging to the third (N+1)^(th) level target controller;determine a first backbone transmission path in response to the firstboundary node and the second boundary node being coupled, wherein thefirst backbone transmission path comprises the source node, the firstboundary node, the second boundary node, and the target node, andwherein the first (N+1)^(th) level controller is further configured to:receive the first backbone transmission path from the first N^(th) levelcontroller; determine a sub-transmission path of the first backbonetransmission path; and instruct each node in the sub-transmission pathto sequentially transmit the data from the source node to the targetnode.
 7. The SDN system of claim 6, wherein the first N^(th) levelcontroller is further configured to: determine a third boundary nodecoupled to the first boundary node and a fourth boundary node coupled tothe second boundary node in response to the second boundary node and thefirst boundary node not being connected; and determine a second primarybackbone transmission path, wherein the second primary backbonetransmission path comprises each of the source node, the first boundarynode, the second boundary node, the target node, the third boundarynode, and the fourth boundary node in response to the third boundarynode and the fourth boundary node belonging to a fourth (N+1)^(th) levelcontroller.
 8. The SDN system of claim 1, wherein the first N^(th) levelcontroller is further configured to send a first broadcast message tothe first (N+1)^(th) level controller, wherein the first broadcastmessage is used to acquire the status information of the first(N+1)^(th) level controller and the status information of the boundarynode of the first (N+1)^(th) level controller, and wherein the first(N+1)^(th) level controller is further configured to: return, based onthe first broadcast message, the status information of the first(N+1)^(th) level controller to the first N^(th) level controller; sendthe first broadcast message to boundary nodes belonging to the first(N+1)^(th) level controller to permit the first (N+1)^(th) levelcontroller to receive status information of the boundary nodes; and sendthe received status information of the boundary nodes to the firstN^(th) level controller.
 9. A software defined network (SDN) controller,wherein the SDN controller is a first N^(th) level controller, wherein Nis an integer greater than or equal to 1, and wherein the first N^(th)level controller comprises: at least one processor; a non-transitorymedia coupled to the at least one processor, wherein the non-transitorymedia is readable by the at least one processor, wherein thenon-transitory media stores instructions that when executed by the atleast one processor, cause the at least one processor to be configuredto: receive a first message from a first (N+1)^(th) level controllerbelonging to the N^(th) level controller when the first messagecomprises an identifier of a node belonging to a different (N+1)^(th)level controller based on status information of each node that ismanaged by the first (N+1)^(th) level controller and that belongs to thefirst (N+1)^(th) level controller; and perform decision processing basedon status information of the first (N+1)^(th) level controller that ismanaged by the first N^(th) level controller and status information ofboundary nodes of the first (N+1)^(th) level controller that belong tothe first N^(th) level controller, wherein the first (N+1) ^(th) levelcontroller belongs to the first N^(th) level controller, and wherein aboundary node of the first (N+1)^(th) level controller belongs to thefirst (N+1)^(th) level controller and couples to a node belonging to adifferent (N+1)^(th) level controller.
 10. A software defined network(SDN) controlling method, comprising: receiving, by a first (N+1)^(th)level controller, a first message from a node belonging to the(N+1)^(th) level controller, wherein N is an integer greater than orequal to 1, and wherein the first message comprises an identifier of thenode sending the first message; sending, by the first (N+1)^(th) levelcontroller, a second message to a first N^(th) level controller to whichthe first (N+1)^(th) level controller belongs in response to determiningthe first message is a cross-domain message comprising an identifier ofa node belonging to a second (N+1)^(th) level controller; sending, byfirst the (N+1)^(th) level controller, a third message to the firstN^(th) level controller based on the first message being a datatransmission request message comprising an identifier of a node notbelonging to the (N+1)^(th) level controller, wherein the third messagecomprises each of an identifier of the first (N+1)^(th) levelcontroller, an identifier of a target node, and a first transmissionpath, and wherein the first transmission path comprises a source nodeand a first boundary node belonging to the same first (N+1)^(th) levelcontroller; receiving, by the first (N+1)^(th) level controller, a firstbackbone transmission path from the first N^(th) level controller towhich the first (N+1)^(th) level controller belongs; determining, by thefirst (N+1)^(th) level controller, a sub-transmission path of the firstbackbone transmission path; and instructing each node in thesub-transmission path to sequentially transmit the data from the sourcenode to the target node.
 11. The SDN controlling method of claim 10,wherein sending the first message to the first N^(th) level controllercomprises: adding, by the first (N+1)^(th) level controller, anidentifier of the first (N+1)^(th) level controller to the firstmessage, to obtain a fourth message in response to the received firstmessage comprising an identifier of a third (N+1)^(th) level controller;and sending, by the first (N+1)^(th) level controller, the fourthmessage to the first N^(th) level controller.
 12. The SDN controllingmethod of claim 10, further comprising: receiving, by the first(N+1)^(th) level controller, a first broadcast message from the firstN^(th) level controller; returning, by the first (N+1)^(th) levelcontroller, based on the first broadcast message, status information ofthe first (N+1)^(th) level controller to the first N^(th) levelcontroller; sending, by the first (N+1)^(th) level controller, the firstbroadcast message to boundary nodes belonging to the first (N+1)^(th)level controller such that the boundary nodes return status informationof the boundary nodes to the first (N+1)^(th) level controller; andsending, by the first (N+1)^(th) level controller, the received statusinformation of the boundary nodes to the first N^(th) level controller.13. A software defined network (SDN) controlling method, comprising:receiving, by a first N^(th) level controller, a first message from afirst (N+1)^(th) level controller belonging to the N^(th) levelcontroller in response to determining the first message comprises anidentifier of a node belonging to a different (N+1)^(th) levelcontroller based on status information of each node that is managed bythe first (N+1)^(th) level controller and that belongs to the first(N+1)^(th) level controller; and performing decision processing based onstatus information of the first (N+1)^(th) level controller that ismanaged by the first N^(th) level controller and that belongs to thefirst N^(th) level controller and status information of boundary nodesof the first (N+1)^(th) level controller belonging to the first N^(th)level controller, wherein a boundary node of the first (N+1)^(th) levelcontroller belongs to the first (N+1)^(th) level controller and couplesto a node belonging to a different (N+1)^(th) level controller.
 14. TheSDN controlling method of claim 13, wherein performing the decisionprocessing comprises determining a backbone topology of an SDN system.15. The SDN controlling method of claim 13, wherein performing thedecision processing comprises determining a backbone transmission pathof data transmission.
 16. The SDN controlling method of claim 13,wherein performing the decision processing comprises: updating thestatus information of the first (N+1)^(th) level controller that ismanaged by the first N^(th) level controller and that belongs to thefirst N^(th) level controller; and updating the status information ofthe boundary nodes of the first (N+1)^(th) level controller belonging tothe first N^(th) level controller.
 17. The SDN controller of claim 9,wherein the at least one processor is configured to add an identifier ofthe first (N+1)^(th) level controller to the first message to obtain asecond message in response to the received first message comprising anidentifier of a third (N+1)^(th) level controller, wherein the sendingport sends the second message to the first N^(th) level controller, andwherein the first N^(th) level controller is further configured to:receive a plurality of third messages from each (N+1)^(th) levelcontroller belonging to the first N^(th) level controller; and determinea backbone topology of an SDN system based on the plurality of thirdmessages; and determine a backbone transmission path of data in the SDNsystem based on the backbone topology.
 18. The SDN controller of claim17, wherein the sending port separately sends a fourth message to thefirst N^(th) level controller and a node belonging to the first(N+1)^(th) level controller, wherein the fourth message comprises anidentifier of the node to which the fourth message is sent and theidentifier of the first (N+1)^(th) level controller, and wherein thefirst N^(th) level controller is further configured to: receive a fifthmessage from a sending port of the first (N+1)^(th) level controller;and determine the backbone topology of the SDN system based on the thirdmessages and the fourth message that comprise an identifier of a samenode to determine the backbone transmission path of the data in the SDNsystem based on the backbone topology of the SDN system.
 19. The SDNcontroller of claim 9, wherein the processor is configured to update thestatus information of a node sending the first message based on thefirst message, wherein the first message comprises the statusinformation, wherein the first N^(th) level controller receives thefirst message when the first message comprises status information of thenode, wherein the node is a boundary node of the first (N+1)^(th) levelcontroller, and wherein the first N^(th) level controller is furtherconfigured to update the status information of the boundary node of thefirst (N+1)^(th) level controller based on the first message.